The popularity of wheeled luggage cases has spawned a multitude of wheel systems, such as, for example, a wheel system consisting of a pair of swivel wheels and a pair of non-swivel wheels at leading and trailing ends, respectively, of the bottom wall of a luggage case, so that the case may be moved along the ground by a pulling strap, and a wheel system consisting of a pair of non-swivel wheels at the trailing end of the bottom wall of a luggage case, so that the case may be pulled along the ground when the leading end of the bottom wall is lifted off of the ground by means of a rigid or semi-rigid pulling handle. Recently, a wheel system has been proposed that consists of a pair of major (larger) non-swivel wheels at opposite sides of the bottom wall of a luggage case centered between leading and trailing end walls, and a single minor (smaller) swivel wheel mounted at each end of the bottom wall centered between the side walls. With such a wheel system, a luggage case may be turned freely about a central vertical axis when the case is pulled by means of a handle at one end of the case.
All of the conventional wheel systems have disadvantages. For example, a wheel system constituted by two swivel wheels and two non-swivel wheels provides limited freedom of movement, and luggage cases employing such wheel systems tend to be unstable when pulled. A wheel system constituted by two non-swivel wheels requires that a user support part of the weight of the luggage case when the case is pulled. A wheel system constituted by two major non-swivel wheels disposed at opposite sides of the bottom wall centered between the end walls and two minor swivel wheels at opposite ends of the bottom wall supports a luggage case on only three wheels (the major wheels and one minor wheel) at any given time, an arrangement that is less stable in certain respects than wheel systems employing four wheels adjacent to respective corners of the bottom wall. Also, the rather large major wheels require a special case construction to accommodate them.